Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04M—TELEPHONIC COMMUNICATION
  • H04M3/00—Automatic or semi-automatic exchanges
  • H04M3/42—Systems providing special services or facilities to subscribers
  • H04M3/56—Arrangements for connecting several subscribers to a common circuit, i.e. affording conference facilities
  • H04M3/561—Arrangements for connecting several subscribers to a common circuit, i.e. affording conference facilities by multiplexing
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04M—TELEPHONIC COMMUNICATION
  • H04M2250/00—Details of telephonic subscriber devices
  • H04M2250/08—Details of telephonic subscriber devices home cordless telephone systems using the DECT standard

Definitions

• the present invention relates to the field of wireless transmission of audio, such as one-way wireless audio streaming. Specifically, the invention proposes a high density DECT based wireless system for communication of multiple audio streams, such as utilizing DECT full slots.
• Traditional wireless DECT technologies are based for star network topologies and is typically suitable for two-way communication between a plurality of portable parts (PP) and a base station (fixed part, FP).
• the FP normally controls all the communication to the PPs and usually provides slot and frame timing information in a master-slave configuration.
• the PPs synchronize precisely to the FP timing.
• the invention provides a method for wireless RF one-way communication of audio data, wherein the method comprising - providing a plurality of portable part devices each being configured to transmit audio data represented in frames each containing a plurality of time slots in a wireless RF signal according to a DECT compatible protocol,
• Such method provides a high capacity wireless RF system allowing a high number of portable part devices, e.g. microphones of a tele conference system, to be used with one fixed part device or base station with the use of a DECT protocol.
• portable part devices e.g. microphones of a tele conference system
• This is possible by means of a common broadcasting of control information to all portable part devices from the fixed part device.
• This allows both uplink and downlink parts of the DECT frames to be used for audio data transmission from the portable part devices to the fixed part device, thereby increasing audio transmission capacity.
• This can be used to increase the number of portable part devices connected to one fixed part (base station), and/or to ensure a higher audio quality for the same number of fixed part devices.
• the method allows that the multi channel audio transmission has a low latency, which is an important parameter for live audio streaming.
• a system comprising a plurality of separate fixed part receiver devices (base stations) operating in synchronization can be used. In this way e.g. up to 80-100 or even more audio channels can be obtained.
• the DECT protocol exists in a number of area or country specific variants. However the invention is compatible with and can thus be exploited in a large part of these specific DECT variants. The below phrases will be used and are therefore explained:
• TDMA Time Division Multiple Access
• CRC Cyclic Redundancy Check
• a single radio event e.g. transmit or receive is denoted a slot or time slot.
• a repeated sequence of slots, including slot(s) for interference scanning (TDMA frame) is denoted a frame.
• the DECT compatible frames are preferably full slot DECT frames, thereby allowing a high number of portable parts with a high audio quality.
• the DECT frames may be long slot frames, double slot frames, or half slot frames.
• one or more time slots in each frame is dedicated to broadcasting said multiplex of control information from the fixed part device.
• two time slots in each half frame may be dedicated to broadcasting said multiplex of control information from the fixed part device.
• the first two time slots in each half frame may be dedicated to broadcasting said multiplex control information.
• any one or two time slots in each frame may be dedicated to broadcasting said multiplex of control information.
• the multiplex control information is preferably contained as multiplexed A-fields in a B-field of one or more slots, such as one or more full slots.
• one slot e.g. a full slot, dedicated for said multiplex control information may comprise an A-field and a B-field, wherein the B-field comprises a header part, an error checking part (e.g. CRC) and a part containing said multiplex control information.
• CRC error checking part
• At least 50%, e.g. 50-80%, of time slots in both first and second half parts of each frame are dedicated for transmission of audio data from the plurality of portable part devices.
• the plurality of portable part devices are preferably synchronized to transmit audio data in respective time slots of each frame.
• more than 8 portable part devices, e.g. 9-16 portable part devices may be synchronized to transmit audio data in respective time slots of each frame, e.g. each transmitting audio data in one time slot per half frame.
• the fixed part device is preferably arranged to receive a total of at least 64 kbps audio data.
• each portable part device can be a stand-alone device including RF receiver and transmitter circuits configured to operate according to the above-defined method.
• the portable part device can include an audio data source, e.g. a microphone with an associated analog to digital converter, or the portable part device can be a dedicated stand-alone audio transmitter device with an analog or digital audio interface to receive an audio signal, e.g. a wireless RF transmitter for transmission of sound from a musical instrument or the like.
• the portable part device can be e.g. a stage microphone, since in addition a low latency is possible.
• a wireless RF device is a teleconference microphone.
• the method is advantageous for wireless audio transmission system where the method offers a trade between 1) number of portable part devices connected to one fixed part device (base station) and 2) audio quality (i.e. bits per second rate) given a wireless RF transmission channel with limited capacity.
• the audio data packets may represent a digital audio signal sampled at a sampling frequency of 20 kHz or more, such as 32 kHz, 48 kHz or more.
• the digital audio signal may be an encoded digital audio signal, such as encoded according to an ADPCM algorithm or the like.
• the method is implemented as a DECT compatible protocol which is compatible with requirements of one or more regional or country DECT compatible variants.
• the method comprises broadcasting in each DECT compatible frame, by the fixed part device, at least one time slot, such as 2-4 time slots, of audio data to the plurality of portable part devices, receiving the at least one time slot of audio data, by each of the portable part devices, and extracting, by each of the plurality of portable part devices, an audio signal in response to the received at least one time slot of audio data.
• another audio feature is added to the one-way audio transmission from the plurality of portable part devices to the fixed part device, namely the possibility to broadcast or multicast one audio signal to all of the plurality of portable part devices.
• the fixed part device, or another device may generate an audio signal in response to the plurality of audio signals received from the plurality of portable part devices, e.g. a mix of said plurality of audio signals, which can them be sent as feedback to the plurality of portable part devices.
• the fixed part device is not capable of a duplex audio communication with the plurality of portable part devices, but merely to transmit or broadcast one common audio signal to all of the plurality of portable part devices.
• each DECT frame may be dedicated to broadcasting said audio data from the fixed part device.
• two time slots in each half frame are dedicated to broadcasting said audio data from the fixed part device.
• two consecutive time slots in each half frame are dedicated to broadcasting said audio data from the fixed part device.
• at least 4 time slots in each DECT frame are dedicated to said multiplex of control information, and wherein at least 4 time slots in each DECT frame are dedicated to said audio data to be broadcast by the fixed part device.
• at least 16 time slots in each DECT frame are dedicated to said audio data to be transmitted from the plurality of portable part devices.
• each DECT frame has: 16 time slots dedicated to audio data from the plurality of portable part devices, 4 time slots dedicated to the multiplex of control information, and 4 time slots dedicated to audio data to be broadcast by the fixed part device.
• the invention provides a wireless RF device comprising at least one RF transmitter and RF receiver circuit connected to at least one RF antenna, the wireless RF device being arranged to operate as the portable part device according to the method of the first aspect.
• the wireless RF device may be arranged to receive audio data represented in at least one time slot in each DECT frame.
• the wireless RF device may comprise an acoustic transducer, such as a loudspeaker, arranged to generate an acoustic signal in accordance with said received audio data.
• the wireless RF device comprises a microphone arranged to capture sound and to generate audio data accordingly, e.g. to serve as a high quality stage microphone or a tele conference microphone, or the like.
• the FP alternatively or additionally include an analog or digital audio interface to receive an audio signal, e.g. a wireless RF transmitter for transmission of sound from a musical instrument or the like.
• the wireless RF device is a headset or a device comprising a combination of a microphone and an acoustic transducer arranged to generate an acoustic signal in response to a received audio signal.
• the loudspeaker may be in the form of an earphone, a headphone or an in-ear device.
• the invention provides an FP configured to operate as the fixed part device according to the method of the first aspect.
• the FP or fixed part device may be a stand-alone device with a multi channel audio output interface with multiple analog and/or digital audio outputs arranged for output of audio signals corresponding to the received audio data from the plurality of wireless RF devices.
• the FP may form part of another device, e.g. an audio device for live performance or studio, such as an audio mixing console.
• the fixed part device may further be arranged to broadcast an audio signal represented as audio data represented in at least one time slot in each DECT frame.
• the invention provides a system comprising a plurality of PPs according to the second aspect, and a FP according to the third aspect.
• the system may especially comprise an audio reproduction system comprising at least one loudspeaker arranged to generate an acoustic output in response to audio data transmitted from at least one of the plurality of PPs and regenerated by the FPs.
• the system may comprise a plurality of FPs according to the third aspect, wherein each of the FPs is arranged to receive audio data from a plurality of PPs according to the second aspect, and wherein the plurality of FPs are configured for synchronized cooperation.
• the system may be one of: a tele conference system, a wireless live performance audio system, a board room conference system, a class room audio system and a committee or conference audio system.
• the system may comprise at least 8, such as 8-16, portable devices configured for wireless RF connection to the fixed part by using audio data transmission in respective time slots of each DECT frame.
• the invention provides use of the system according to the fourth aspect for one or more of: a tele conference system, a wireless live performance audio system, a board room conference system, a class room audio system and a committee or conference audio system.
• the invention provides a program code comprising first and second code parts arranged to cause the method according to the first aspect to be performed, when the first code part is executed on a processor in a plurality of portable part devices (e.g. according to the second aspect), and when the second code part is executed on a processor in a fixed part device (e.g. according to the third aspect).
• the first and second code parts may be stored in memory in respective chips of respective first and second devices, or on one or more tangible storage media, or available on the internet in a version for downloading.
• the first and second code parts may be in a general code format or in a processor dedicated format.
• FIG. 1 illustrates a simple block diagram of a system of three portable part devices in one-way audio transmission to a fixed part device which broadcasts control information to the wireless RF devices according to a DECT protocol
• FIG. 2 illustrates steps of a method embodiment
• FIG. 3 illustrates an example of a DECT frame with control information from the fixed part and audio data from the portable parts in each half frame
• FIG. 4 illustrates an example of a possible use of a full slot for broadcasting a multiplex of control information to a plurality of wireless RF devices
• FIG. 5 illustrates an example of components of a wireless RF microphone device and a corresponding wireless RF receiver device
• FIG. 6A and 6B illustrate examples of DECT frame configuration for embodiments with multicast audio to the plurality of wireless RF devices.
• FIG. 1 shows a simple illustration of three wireless RF devices, portable parts, PPI, PP2, PP3, each being arranged to communicate respective audio signals ADI, AD2, AD3 represented in digital data packets transmitted in an RF representation via a DECT based protocol to a wireless RF receiver device, fixed part or base station.
• the fixed part device (FP) regenerates the received audio data into respective audio signals Al, A2, A3.
• the portable part devices PPI, PP2, PP3 are synchronized by means of control information transmitted from the fixed part device (FP) as broadcast common information BC transmitted to all of the portable parts devices PPI, PP2, PP3 in time slots one or more time slots in each DECT frame.
• FIG. 2 illustrates steps of a wireless RF communication method embodiment for RF communication of a plurality of digital audio data according to a DECT protocol.
• P_PPx a plurality of portable part devices each being configured to transmit audio data represented in frames each containing a plurality of time slots in a wireless RF signal according to a DECT compatible protocol
• P_FP a fixed part device configured to receive said wireless RF signals from the plurality of portable part devices and to regenerate the respective audio data represented therein.
• the method comprises broadcasting B_CI in each DECT frame, by the fixed part device, a multiplex of control information to the plurality of portable part devices, e.g.
• the portable part devices containing information regarding synchronization information to allow the portable part devices to transmit their audio data in different predetermined time slots of each frame.
• the fixed part device receives a stream of frames and thus performs the step of regenerating audio signals according to the transmitted audio data transmitted from the respective portable part devices.
• FIG. 3 illustrates an example of implementation of the invention, where it is seen that both time slots TS in the TX and RX parts of each DECT frame are utilized for audio data transmission from PPs, here 8 denoted PP0-PP7, to the FP.
• PPs here 8 denoted PP0-PP7
• B-field modulation being n/4-DQPSK modulation
• 1280 bits are available for payload data.
• CRC 16 bit CRC is used (one for each transmission), resulting in 1248 bits/frame for the encoded audio (124,8 kbps).
• each 10 ms DECT frame is divided into 24 time slots TS, and the first two slots in each half frame, i.e. a total of 4 time slots, numbers 0, 1, 12 and 13, are dedicated to the fixed part FP broadcasting control information which is received by all PPs.
• each PP has two dedicated time slots, one in each half frame, for transmission of audio data.
• PP0 transmits data in time slot TS numbers 2 and 14.
• the proposed DECT frame design provides a double simplex connection, since instead of having a return channel in the second half of the DECT frame, 5 ms of audio is transmitted in each half frame.
• a DECT full slot double simplex bearer connection Using a DECT full slot double simplex bearer connection, a 124,8 kbps audio bandwidth from PP to FP can be obtained and supports up to 8 PPs to be connected to one FP.
• the theoretical maximum density of microphones is 104 (by using 13 synchronized FPs), but a density of up to 80 (10 synchronized FPs) is more preferred (This example holds for products operating in the European Union).
• FIG. 4 illustrates an example of implementation of one full slot which the FP broadcasts to all PPs.
• the full slot contains a B-field of 640 bits, but including a header and a multiplex of A-field data channels allocated to each PP.
• a PP will during the handover occupy two A-field data channels on the broadcast.
• FIG. 5 illustrates elements of a specific embodiment of the portable part device (PP) in the form of a wireless microphone, and the corresponding fixed part device (FP).
• the PP has a microphone connected to an analog-to-digital converter A/D which receives the analog audio signal from the microphone and converts it into a digital format, e.g. operating at a sample frequency of 48 kHz, and applies the digital signal to a digital encoder which is followed by a CRC calculation and finally applies the resulting data for an encryption (AES256), and finally the resulting signal data is RF transmitted in the predetermined time slots of the DECT frame.
• AES256 an encryption
• the fixed part device FP receives the audio data packets from the PPs, and performs the reverse processing, including decoding audio data from each of the PPs, and the resulting audio signals are then applied to further processing, which may include Acoustic Echo Cancellation (AEC), a mixing and further sound processing before the final audio output is generated - e.g. as a mix of the plurality of audio signals regenerated from the PPs down to one or two separate audio channels.
• AEC Acoustic Echo Cancellation
• the total latency that can be obtained is about 24 ms, and this latency is constant for all PPs.
• FIG. 6A and 6B show two different DECT frame configurations for embodiments with an audio multicast channel for broadcasting of an audio signal to all of the plurality of portable part devices.
• one DECT frame has 24 time slots, and it is split into two identical parts each with 12 time slots, and wherein:
• time slots are dedicated to audio data from the plurality of portable part devices
• time slots are dedicated to multiplex control information to the plurality of portable devices
• time slots are dedicated to broadcast or multicast audio data from the fixed part device to the plurality of portable part devices.
• FIG. 6A two consecutive time slots are dedicated to the broadcast or multicast audio data in each half frame.
• FIG. 6B the two time slots dedicated to the broadcast or multicast audio data in each half frame are separated by the 8 time slots dedicated to audio data from the plurality of portable part devices.
• the invention provides a wireless communication method and protocol for wireless RF transmission of audio data from a plurality of wireless RF devices (portable parts PP) to a wireless RF receiver device (fixed part FP) using a full slot DECT protocol.
• the FP broadcasts in each frame, a multiplex of control information to the plurality of PPs.
• the PPs receive the multiplex of control information, and extract control information intended for each individual PP from the multiplex of control information.
• the PPs are synchronized to transmit audio data in respective time slots covering both time slots in first and second half of the frame.

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• 2021
  • 2021-10-14 CN CN202180073700.1A patent/CN116830482A/zh active Pending
  • 2021-10-14 US US18/250,836 patent/US20230396711A1/en active Pending
  • 2021-10-14 EP EP21791374.8A patent/EP4238301A1/en active Pending
  • 2021-10-14 JP JP2023525971A patent/JP2023547200A/ja active Pending
  • 2021-10-14 AU AU2021369174A patent/AU2021369174A1/en active Pending
  • 2021-10-14 WO PCT/EP2021/078474 patent/WO2022089949A1/en active Application Filing

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